Rotary scraper, abrading, or polishing tool



Jan. 1954 w. c. E. PRINS ET AL ROTARY SCRAPER, ABRADING, OR POLISHINGTOOL 2 Sheets-Sheet 1 Filed April 3, 1951 Jan. 5, 1954 w. c. E. PRINS ETAL 2,664,586

ROTARY SCRAPER, ABRADING, OR POLISHING TOOL Filed April 5, 1951 2Sheets-Sheet 2 Enventors Patented Jan. 5, 1954 ROTARY SCRAPER, ABRADING,OR POLISHING TOOL Winston C. E. Prins and Dougal W. S. Prins,Washington, D. 0.

Application April 3, 1951, Serial N 0. 219,082

15 Claims.

This invention relates to a rotary scraper, abrading or polishing tool.

The tool as described herein and as depicted in the drawings attachedhereto is adapted for many uses, viz., cleaning the hulls of ships orboats, large boilers and preparing surfaces for a ground coat of paintor the like and further by utilizing certain hereinafter describedspecial type of blades. Rather than producing a scraping or cuttingaction such special blades are of the abrasive or polishing type andeffect a polishing or finishing or buffing or planishing action onvarious surfaces and articles which may consist of or be fabricated fromglass, metal, wood, plastic, or combinations of same.

The present tool is of the rotary type and includes generally anexterior stationary shell with a shell concentrically disposed thereinand which latter shell is rotatable and carries thereon a plurality ofcutting, scraping, abrasive or polishing blades, as the case may be, andwhich blades un-- der centrifugal force due to rotation of the innershell will move outwardly and their outer end portions will emerge orproject beyond the axial face portions of the inner and outer shells.The inner shell while so rotating relative to the outer shell willproduce the scraping, cutting, abrading or polishing action on thearticle or device or other surface under controlled conditions ofoperation. These controlled conditions of operation are such that theblades will, as aforesaid, be ejected or moved outwardly beyond the faceor axial face portion of the tool under centrifugal force and if thetool is pressed against the work naturally the blades will be retractedsomewhat and as each blade operates independently of the other bladesthe blades will automatically adapt themselves to the work whether it befor cutting, scraping, abrading or polishing purposes in finishing workor otherwise removing some surface portions of the work.

Further, this rotary tool which embodies the aforementioned inner andouter shells, the former having the blades movably associated therewith,is connected with a flexible hose or the like which hose is in turnconnected or associated with a vacuum or suction producing device sothat the surface portions that have been removed from the work, whateverthe work may be, are collected in the vacuum or suction producing devicewhich may be a container or the like or under certain circumstances thesaid removed material may be ejected through the hose that is connectedwith the tool to any source of discharge and need not be confined in thevacuum or suction producing device as this last mentioned device may notbe utilized or embodied with the tool.

Furthermore, in connection with the present rotary tool the inner shellis concentrically and specially anti-frictionally mounted within theouter shell so that ease of rotation of the inner shell relative to theouter shell is readily accomplished and this rotation may be effected bya simple electric motor drive that is gear or otherwise connected withthe interior shell but, of course, other sources of driving the innershell may be employed, such as a power take-off from any motor or otherpower driven source.

Additionally, the present rotary tool is comprised of a minimum numberof very simple component and cooperative elements all of which may beassembled in final form by unskilled workmen and which parts can all beprefabricated and assembled rapidly and properly in a minimum of time.Moreover, the structural component cooperative elements comprising thepresent tool are relatively inexpensive to manufacture and assemble.

As shown and described herein the invention may take the form of acompact portable unitary device which comprises the aforesaid inner andouter shells, the former shell carrying the blades thereon, and whichblades are centrifugally emerged partly from the inner shell when in useand the outer shell preferably having connected therewith a flexiblehose and a relatively small horse-power motor such as utilized inconnection with rotary drills which serve to drive and rotate the innershell and the motor of this driving means being preferably triggercontrolled to allow ease of operation on the part of the operator andthe hose being connected with a vacuum or suction producing device inthe form of a container whereby the material, whatever it may be, thatis removed from the surface of the work that is being treated iscollected in the inner shell and flows into the hose under suction orvacuum into the container and, of course, the container has meansembodied therewith so that the said collected material can be removedfrom the container.

With these and other objects in view, the invention consists in theconstruction and novel combination and arrangement of parts hereinafterfully described, illustrated in the accompanying drawings and pointedout in the claims hereto appended, it being understood that Variouschanges in the form, proportions, and minor details of construction,Within the scope of the claims, may be resorted to Without departingfrom the spirit of or sacrificing any advantages of the invention.

In the drawings:

Fig. 1 is a perspective view of the complete assemblage of the rotarytool;

Fig. 2 is a sectional view substantially along the lines 2-2 of Fig. 1,looking in the direction of the arrows and showing certain parts inelevation;

Fig. 3 is an exploded view showing the inner shell partly in sectitonand the reduction gear for the inner shell in perspective and portionsof the inner ball races in perspective;

Fig. 4 is an enlarged perspective view of the head portion of the rotarytool with certain parts broken away and shown in section;

Fig. 5 is an enlarged sectional View of one of the fins or ribs uponwhich the individual scraping or cutting blades or the like is carried;and

Fig. 6 is a perspective View of one of the scraping or cutting blades orthe like, as the case may be.

Similar reference numerals or characters in the several figures of thedrawings all denote the same component elements or parts.

The invention will be more readily understood by referring to thedrawings in detail. In Fig. l of the drawings the overall tool orassemblage is disclosed. The overall assemblage comprises the outerstationary shell l, and the inner blade carrying rotatable shell 3which, as will be noted, is concentrically disposed within the saidouter shell. These shells and the integral parts thereof later referredto constitute the entire head of the tool generally indicated at 9. Theouter shell 7 is substantially circular in outline and is hollow andincludes the substantially cylindrical inner wall iii which iscompletely open at the front thereof l i and is closed by the rear walli2. This rear wall i2 has a centrally disposed outwardly extendingexteriorly screw threaded extension or neck is integral therewith. Thisextension i3 is hollow or provides an opening 54, and substantially inline with the rear wall !2 there is a circular convex seat or entrancel5 merging into the opening id for a purpose later described.

As will be noted from Fig. 2, there is a slight clearance is between theouter periphery of the inner shell 8 and the inner peripheral wall ofthe outer shell 1 which enables the insertion of the anti-frictionmeans-the balls or spheres, ball races, and locking rings hereinafterdescribed. Ihe inner shell 8 conforms generally with the inner contourof the outer shell '3 and it, like the outer shell, has a rear wallportion if and there is a centrally outwardly extending exterior screwthreaded extension or neck 58 and the extreme exterior end portion 555of the extension 5'8 is circularly concave and substantially conforms inshape to the convex interior portion l5 of the extension E3 on the outershell. This concave formation is terminates at 2d and forms an outletfor the inner shell 8 and is slightly inside of the opening it in theextension it of the outer shell H. As a matter of fact the circularconcave portion 2! of the extension 58 preferably slightly contacts andbears against the corresponding convex portion at the entrance of theopening it in the extension 53 of the outer shell 1 and this serves as apartial closure or retricted juncture of the two shells, with the spacebetween shells exhausted by virtue of the suction hereinafter described,

The exteriorly screw threaded extension E8 of the inner shell 3 hasmounted thereon the inte-- riorly screw threaded reduction gear 22. Thescrew threads E8 are left hand screw threads so that when the innershell is rotated clockwise, as hereinafter more fully described, thegear will have a tendency to constantly tighten itself on these screwthreads. Of course, if desired, the gear could be integral with theshell or keyed thereto rather than being screw threadedly mountedthereon or it can be secured or carried thereon in any desired manner.

Substantially the entire peripheral portion 2% of the inner rotatableshell 8 is in the form of relatively coarse screw threads andcorresponding screw threads 25 are likewise on the inner peripheralsurface of the outer stationary shell I.

These corresponding screw threads serve as a means for associating apair of inner and outer ball races and a ring of balls correspondingwith these races with the inner and outer shells. The pair of inner ballraces is denoted at 25 and 2'? while the pair of outer ball races isdenoted at 28 and 29. The inner ball races each has similar interiorscrew threads 38 thereon and these scre v threads correspond to thescrew threads 2 on the periphery of the inner shell 8. The pairof outerball races 23 and 29 each has similarly formed exterior screw threads 3!thereon and these screw threads correspond to the interior screw threads25 of the outer shell There are also provided interior and exteriorlocking rings 32 and 33 for the pairs of ball races 26-2l and 2t29respectively. These locking rings 32 and 33 are respectively providedwith interior and exterior screw threads 32 and respectively and thesescrew threads correspond with the screw threads 2 and 25 respectively.

We may utilize a flat seal rin 33, which seal ring is brazed orotherwise permanently ciated with the outer face portion of the outerlocking ring 33. This seal ring 33, it will be noted, closes the passagebetween the spaced apart pairs of ball races 2t2'i and 28 253 and theirassociated locking rings 32 and 33.

When the interior shell 8 is positioned concentrically within the outershell l the said pairs of ball races are screw threaded-1y associatedwith the interior and exterior shells as shown particularly in Figs. 2and 4 and the locking rings 32 33 serve to maintain or hold these ballraces in their proper positions. With the inner race and the outer race23, firmly run up to the termination of screw threads 2 of th inner raceand 25 of the outer shell respectively, the balls or spheres B may beplaced on the surfaces 38 and 33, respectively. Then the complementaryraces of the pairs 27 and 2% ma be run up so that their surfaces 3'? and39, respectively also bear upon the balls or spheres B. The portionsdenoted S and S of the inner and outer races respectively are in factthe ends of the internal screw threads on the outer race and serve asabutments or stops to position and align the inner and outer races. Inother words these portions S and S are the ends of the threads of theinner and outer races.

The inner shell 8 is provided with a plurality of preferably similarlyformed spaced ribs or fins 48. A description of one of these fins willsufice for all of them. Each rib or fin 4%}, as will be clearly seenfrom Fig. 3, is cast integral with the inner rotatable shell 8 and isprovided with an outer free end ii and a free side edge &2, while theremainder thereof is, as aforesaid, inte ral with the shell itself. Eachof these ribs has a cutter or scraper, abrasive or polishing meanscarried by and supported on the forward face :13 thereof. Thissupporting face or surface at of each of the fins or ribs id ispreferably at a angle relative to the rear wall portion ll of the innershell 8 and tangent to the outlet 2% of inner shell 8, and the oppositeface M of the rib may be slightly inclined from the perpendicular to therear wall ii. In cross section the aforesaid ribs or fins ts aresubstantially triangular in shape. The angulated supporting surface 63of each of i 1 I 1 e a :ansaarrr a s ieleinaiter described, are movablymounted on this support-- ing surface. The means to maintain the bladesor a blade on each fin till may consist of the exterlorly headed andthreaded bolt 55 which can be cast in each fin or rib 40 as clearlyshown in Fig. 5 and this threaded bolt extends outwardly from thesupporting surface 43 preferably normal thereto, there being two suchbolts for each fln or rib 40, see Fig. 3. The blades D are substantiallyrectangular in outline and are preferably relatively flat on theiropposite surfaces. Each blade is provided with a pair of elongatedsimilarly formed enclosed aligned spaced slots 46 which slots are at a45 angle with respect to the rear edge ll of the blade. These slots 46are so positioned on each blade D that they register with the twothreaded bolts 45 carried by each rib or fin 4i]. Substantiallyrectangularly shaped spacers it, which spacers ar provided with openingstherein of substantially the same diameter as the bolts 45, aresuperimposed on the rear pore tions of each of the blades and, ofcourse, the bolts extend through spaced openings 49 in each of thesespacers The spacers 48 and the movable blade D are maintained on thesupporting surface 43 by the bolts 45 and the castellated interiorlyscrew threaded nuts N and these nuts N are maintained in their properposition on the bolts 45 by means of a cotter key 5!) which passesthrough a transverse opening 5| in each of the bolts.

It will be understood that the bolts are not tightened against thespacers 48 so as to produce a binding action, there being enoughtolerance between the bottom of the spacers and the outer face portionD' of each blade D so as to allow a sliding movement of each of theblades on the supporting surface 53 when the inner shell 8 is rotatedand this sliding movement being induced or caused by centrifugal actionupon the blades. The outer edges M of each of the fins or ribs 40 issuch that when the blades are in inoperative position, as shown in thedotted lines in Fig. 5, the extreme outer edges E of the blades areslightly behind the extreme outer edge 41 of each of the ribs. Whereaswhen the blades are under centrifugal action the extreme outer endportion thereof as seen in Fig. 5 will project beyond the extreme outerend portions 4| of each of the ribs. Since the blades project from theshell during use of the device and are held in the extended position byforwardly deflected centrifugal force, outer ends of the blades Will beyieldably held in position for contact with a surface to be operatedupon and may yield sufiiciently to follow irregularities in the surface.

It will be noted from Fig. 6 that the lower left corner 41' of the bladeD is square. The square corner portion of the blade is adapted to beguided by and in spaced recesses or grooves G in the inner wall of theinner shell 8. Obviously, there is one of these grooves G adjacent thebase of each of the fins that are integral with the interior of theinner shell.

The blades D, if utilized for scraping or cutting purposes, arepreferably formed of metal and are rigid. When the inner shell 8 isrotated clockwise as viewed in Fig. 1 the edge portion E effects thecutting or scraping action. However, it is to be distinctly understoodthat in lieu of the blades D, we may utilize blades which may be formedof Carborundum or other abrasive type blades. Then too, instead of beingeither abrasive, scraping or cutting blades the blades may be formed ofmaterials which would produce a polishing action on the work and furtherit is conceivable that somewhat resilient or flexible blades bothmetallic and non-metallic may equally well be utilized as manifestly nomatter what function the 6. blades perform the centrifugal action'toemerge the outer edges of these blades is inherent in the tool.

The flexible hose which may be fabricated from any suitable materialsuch as rubber or plastic materials is denoted at H. One end of thishose or flexible'conduit h is slipped over a reduced coned extension l3of the exteriorly screw threaded extension 13 and this end portion h ofthe hose or the like is flared to the tool by means of a hollowinteriorly screw threaded cap nut C which has a coned opening therein 0that surrounds the hose. The interior screw threads of this cap nutcorrespond with the screw threads I3 on the central extension of thestationary shell i at the rear wall thereof and when these screw threadsare interengaged obviously the cap nut will serve to retain the end h ofthe hose on the tool. The other end of the hose 52 is attached to thevacuum container V by means of a cap nut 53 which is similar to the capnut C, or any other connection with the vacuum container may beutilized. This container V can either have its top or bottom removablefor access thereto or it may be provided with an exteriorly screwthreaded substantially circular removable closure 54 in its top.Contained within the vacuum or suction chamber V there is a conventionalrotary gear type pump or other such pump or fan that is motor driven forproducing the suction or vacuum through the hose H and in the interiorof the rotatable shell 8. As the pump or fan, as the case may be, isconventional the same is not shown. An electrical conductor 55 extendsinto the interior of the chamber or container V and is connected withthe pump or motor therein and the end of this conductor is provided witha three or four pronged quick detachable connector 56 that may beplugged into any suitable source providing electric current for theoperation of the suction producing pump or fan within the chamber orcontainer V.

The inner rotatable shell 8 is rotated by a conventional electric drilltype motor M that is provided with a hand grip 51 and a trigger electricswitch 58 adapted for ready control by the operator. Thismotor M hasconnected therewith an electric conductor 59 which also has the quickdetachable three or four pronged connector 66 therein which is adaptedto be plugged in any suitable source of electric current.

The motor M has a rotatable shaft Bl projecting outwardly therefrom andthe extreme end of this shaft 62 is preferably in the form of gear teethwhich correspond with the exteriorly extending gear teeth on the gearring 22 that is mounted on the inner rotatable shell 8. The mounting forthe motor shaft 6| is preferably an anti-frictional one denoted at 53.This anti-friction bearing 63 is substantially identical in structurewith the inner and outer bearing recesses 26-27 and 28 89 respectivelyas hereinbefore described and the same is screw threaded similarly tothe races 26-2l and 28-29, with the outer races screwed within a hollowcircular cast or inserted boss 64, which boss extends outwardly from therear wall i2 of the outer shell I and to one side of the extension l3.The inner races, it will be noted, are screw threaded on the shaft 6|.The shaft Si is thus secured relative to the outer shell I for properassociation in driving the ring gear 22 andto effect rotation of thatgear and consequently rotation of the inner shell 8 relative to theouter shell.

The operation of the tool is indeed simple.

Having selected the particular type of blades whether they be cutting,scraping, polishing, planishing or other type blades and whether suchblades be metallic or non-metallic and rigid or possessing flexible 'orresilient characteristics and mounting these blades on the studs orbolts it, as aforesaid, all that is required of the operator is to plugin the connectors 56 and '60 and then by gripping the driving motor M onthe portion thereof and depressing and pressing the trigger 53 the innershell will immediately rotate and the blades under centrifugal actionwill simultaneously emerge and the ends of the blades under centrifugalaction will emerge beyond the axial face of the tool and the toolapplied to the work' to perform its function. The material, whatever maybe, that is removed from the work enters the inner shell and exitsthrough the central extension in the shell into the opening id of theouter shell and hence through the hose or other flexible conduit H intothe container V. In operation the blades being individually mounted formovement relative to the inner shell will adapt themselves, each one ofthem, to the contour of the particular work. If the surface that isworked on is flat then, of course, each blade will project or emergeoutwardly substantially the same distance from the axial face of thetool, but if the surface is irregular then each blade will automaticallyeither be emerged or retracted and follow the surface across which itmoves during the rotation of the head 3.

While we have shown the vacuum or suction producing chamber V, undercertain circumstances it may be desirable to eliminate this containerand substitute therefor a conventional Venturi means in the hose H orutilize a steam or hydraulic jet to produce the suction or vacuum inthis hose for removing the material from the interior of the rotatableshell 8. In such event the end 52 of the hose could be unattached andthe detritus or removed material from within the hose could bedischarged into a container or into a stream or any other'suitabledischarge. Where the removed material is flaky or dust-like it ispreferable, however, to utilize the container or chamber V and collectthis mateial for later discharge.

The head of the tool 9 may be madeof various diameters and, of course,this head includes the inner and outer shells and the speed of rotationof the inner shell may vary depending-upon the work that the blades orthe like are to perform. Likewise, the type of motoras regardshorsepower may be varied depending upon the type of work that the toolis to perform. Other driving means in lieu of an electric motor may beused employing similar simplicity of controls. vVhile manual support,operation of the controls, and manipulation of the tool head depictedare intended, it may also be envisioned that the basic principles of thetool head herein described are equally applicable to :a mechanicallysupported and/or manipulated tool head and/or with-auto matic orsemi-automatic control devices which embodies the unique characteristicsof said tool head.

As to the anti-friction means which consists of pairs of inner and outerball races 26- 21 and 28-29 respectively and the ring of balls 3, theinclined opposed bearing surfaces or race paths 3B and 3? of the innerball races are ofl5 while the opposed bearing surfaces or race paths ofthe outer races and are 52 with the transverse 8 plane perpendicular tothe inner shell axis passthrough the centers of the balls or spheres B.This particular disposition of the opposed race paths of the inner andouter races avoids friction and the extent of rotation of the balls onthe inner races is equal to the rotation of the balls on the outerraces.

Six ribs or fins 40 and likewise six blades 1) are disclosed in thedrawings. It is to be understood that any number of such ribs and bladesmay, however, be utilized. For instance, it is conceivable that one riband one blade might suffice under certain conditions while two or moreof such ribs and blades would be required under other conditions. Inother words, the number of ribs and blades that may be utilized isoptional.

In addition to serving as a supporting means for the blades the ribs orfins as also considerably reinforce and strengthen the inner rotatableshell 8.

We claim:

1. A rotary tool of the character described comprising a rotary shellrotatable about a'longitudinal axis and open at one end, operatingmembers shiftable through the open end of the shell from a retractedposition to an extended position for use, said operating members havingradial movements imparted'to'them by centrifugal force exerted duringrotation of the shell, and guide means engaged by said operating membersand constituting cams shifting the operating members outwardly throughthe open end of the shell to an extended position for use durin theirmovement by the centrifugal force.

2. The structure of claim 1 wherein the guide means for each operatingmember consists of pins passing through diagonally extending slotsformed through thesaid operating member, said pins limiting movement ofthe operating members through the open end of the casing as well asimparting longitudinal movement to the operating members.

3. The structure of claim 1 wherein the operating members haveside-by-side engagement with webs in the shell, the guide means forshifting the operating members longitudinally consisting of pinsprojecting laterally from the webs and passing through diagonallyextending slots formed through the operating members, nuts screwedupon'said pins, spacer means about said pins between the operatingmembers and said nuts, and fasteners releasably holding the nuts inadjusted position upon the pins.

4. A rotary tool of the character-described'comprising a rotatablecarrier rotatable about a longitudinal axis and having front and rearends,

operating members slidably carried by said carrier and shiftableradially and forwardly thereof, the radial movement being in response tocentrifugal force created during rotation of the carrier, and guidemeans for limiting movement of the operating members relative'to thecarrier and directing the operating members forwardly to an extendedoperative position simultaneously with their radial movement by thecentrifugal force.

5. The structure'of claim' i wherein the means for directing theoperating members forwardly also serves to limit sliding movement ofthe'operating members.

6. A rotary tool of the character described comprising a rotatablecarrier having an edge portion and serving to create centrifugal forcewhen rotating, spaced-apart operating members slidably mounted forlimited movement on said carrier, each member being adapted for independent movement relative to each other and to the carrier from aretracted position forwardly to an extended operative position partiallybeyond the said edge portion of the carrier in response to centrifugalforce created by rotation of the carrier, and cooperative means on thesaid members and said carrier for permanently maintaining each operatingmember in sliding engagement with the carrier and to allow for theindependent movement of the members relative to each other and to thecarrier when the carrier is rotated.

7. A rotary tool'of the character described comprising a rotatablecarrier having front and rear portions and being rotatable about alongitudinal axis and serving to create centrifugal force when rotating,spaced-apart operating members slidably carried by said carrier andmounted for independent movement relative to each other and to thecarrier from a retracted position forwardly to an extended operativeposition partially beyond the carrier in response to centrifugal forcecreated during rotation of the carrier, the carrier and the operatingmember being provided with cooperating means for permanently maintainingthe members in limited slidable engagement with the carrier and to allowthe independent movement of the said members relative to each other andto the carrier to occur when the carrier is rotating.

8. A rotary tool for performing cutting, scraping, finishing orpolishing functions comprising a rotatable shell having an open outerend, blades Within said shell slidably mounted for limited movementradially and axially of the shell, means for rotating the shell andcreating centrifugal force to move the blades radially, and means withinthe shell engageable by the blades as they are moved radially tosimultaneously impart the axial movement to the blades to cause them topartially emerge axially through the open end of the shell.

9. A tool as defined in and by claim 8 wherein the said shell isconcentrically disposed within an outer shell also having an open outerend, bearing means between the inner and outer shells rotatably mountingthe inner shell, and the emergence of the blades axially from open endsof the shells being induced by outwardly deflected centrifugal actionthereon created while the inner shell is rotating.

10. The tool as defined in and by claim 9 where in the bearing meansconsists of inner and outer ball races, the ball races having opposedrace paths thereon and a ring of balls contacting the said paths duringthe rotation of the inner shell relative to the outer shell, and meansfor maintaining the ball races in position relative to the inner andouter shells.

11. A rotary tool of the character described comprising inner and outershells concentrically disposed one within the other and in spacedrelation to each other, both shells having open front ends, the innershell being rotatable relative to the outer shell, blade supporting ribsdisposed within and integral with the inner shell and extendingsubstantially radially thereof, a blade movably supported on each of theribs and shiftable thereon radially of the inner shell and outwardlyaxially of the inner shell through the front end thereof, anti-frictionbearing means between the two shells, means for rotating the inner shellrelative to the outer shell and creating centrifugal force to move theblades radially, and guides carried by said ribs and engaging diag- 1donally extending portions of the blades and individually moving theblades forwardly through open ends of the shells as the blades are movedradially of the inner shells under centrifugal influence.

12. A tool of the character described comprising inner and outer shellsdisposed one within the other in spaced concentric relation to eachother, each of the shells being open at its front end and having a rearwall portion carrying a rearwardly projecting centrally located hollowextension, the said extensions being aligned with each other andproviding a throat extending rearwardly from the inner shell andoutwardly from the outer shell, said inner shell being mounted forrotation in the outer shell, driving means for rotating said inner shelland creating centrifugal force, blade mounting means carried by theinner shell, a blade movably carried on the blade mounting means andshiftable radially of the inner shell and forwardly from a retractedposition within the inner shell to an extended position through the openfront end thereof, guide means carried by said mounting means andengaging said blade and shifting the blade forwardly as the blade movesradially, a hollow conduit connected at one end with the exten ion onthe outer shell and communicating with the throat formed by the saidextensions, the conduit at its other end having suction producing meansconnected therewith, driving means exteriorly of the outer shell andincluding a shaft extending through the outer shell and connected withthe inner shell to rotate the same and thereby create the centrifugalforce exerted on the blades during rotation of the inner shell andeffect movement of the outer end portion of the blade from the openfront ends of both shells to perform their functions of removing surfaceportions from work, the removed surface portions passing into the saidthroat and through the hollow conduit into the suction producing means.

13. A tool as defined in and by claim 12 wherein there are integral ribsin the inner shell eX- tending radially thereof and blades are movableradially and forwardly of the said ribs, a gear ring carried by andextending about a portion of the inner shell, the driving shaft beingprovided with a gear meshing with the said gear ring for rotating theinner shell relative to the outer shell and creating the centrifugalforce which is exerted on the blades and causes outer end portions ofthe blades to emerge from the open ends of the inner and outer shellsduring use of the tool.

14. A tool as defined in and by claim 13 wherein the blades engagesupporting surfaces on the ribs and such surfaces are angularly disposedwith respect to a rear wall of the inner shell.

15. A tool as defined in and by claim 14 Wherein the angulatedsupporting surfaces are at substantially a 75 angle relative to a rearwall of the inner shell.

WINSTON C. E. PRINS. DOUGAL W. S. PRINS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 409,743 Gail Aug. 27, 1889 1,641,103 Small Aug. 30, 19272,168,692 Vidal Aug. 8, 1939 2,504,643 Burgoon Apr. 18, 1950

